Fouling-Release Surface

Research Article www.acsami.org

Semifluorinated Synergistic Nonfouling/Fouling-Release Surface Binbin Xu,† Yajing Liu,‡ Xiaowen Sun,§ Jianhua Hu,*,§ Ping Shi,‡ and Xiaoyu Huang*,† †

Key Laboratory of Synthetic and Self-Assembly Chemistry for Organic Functional Molecules, Shanghai Institute of Organic Chemistry, Chinese Academy of Sciences, 345 Lingling Road, Shanghai 200032, People’s Republic of China § State Key Laboratory of Molecular Engineering of Polymers, Department of Macromolecular Science, Fudan University, 220 Handan Road, Shanghai 200433, People’s Republic of China ‡ State Key Laboratory of Bioreactor Engineering, East China University of Science and Technology, 130 Meilong Road, Shanghai 200237, People’s Republic of China S Supporting Information *

ABSTRACT: The preparation of a fluorine-containing synergistic nonfouling/fouling-release surface, using a bPFMA−PEO asymmetric molecular brush possessing both poly(ethylene glycol) (PEO) and poly(2,2,2-trifluoroethyl methacrylate) (PFMA) side chains densely distributed on the same repeat unit along the polymeric backbone, is reported. On the basis of the poly(Br-acrylate-alkyne) macroagent comprising two functionalities (alkynyl and 2bromopropionate), which is prepared by reversible addition− fragmentation chain transfer homopolymerization of a new trifunctional acrylate monomer of Br-acrylate-alkyne, b-PFMA−PEO asymmetric molecular brushes are obtained by concurrent atom transfer radical polymerization and Cu-catalyzed azide/alkyne cycloaddition “click” reaction in a one-shot system. A spincast thin film of the b-PFMA−PEO asymmetric molecular brush exhibits a synergistic antifouling property, in which PEO side chains endow the surface with a nonfouling characteristic, whereas PFMA side chains display the fouling-release functionality because of their low surface energy. Both protein adsorption and cell adhesion tests provided estimates of the antifouling activity of the asymmetric molecular brush surfaces, which was demonstrated to be influenced by the degree of polymerization of the backbone and the length of the PEO and PFMA side chains. With compositional heterogeneities, all asymmetric molecular brush surfaces show considerable antifouling performance with much less protein adsorption (at least 45% off, up to 75% off) and cell adhesion (at least 70% off, up to 90% off) in comparison with a bare surface. KEYWORDS: molecular brush, antifouling surfaces, nonfouling, fouling-release, spin-casting

■

INTRODUCTION In the past many years, biofouling, a worldwide problem caused by the adhesion and accumulation of organisms on surfaces, has a serious impact on the marine industry and medical devices.1−6 Antifouling materials, which modify the surface physicochemical properties to suppress biofouling, have been greatly used in a wide range of applications.7−9 Considerable research efforts have been reported for antifouling materials, in which antifouling polymer surfaces may serve as an attractive weapon to mitigate biofouling because precise control of their architecture and composition can significantly improve their antifouling performance.3,7,10−15 Three general techniques of self-assembly,16 grafting-from,17,18 and grafting-onto19,20 have been widely used for preparing antifouling polymer surfaces. The self-assembly approach is limited to special interactions (such as aromatic or electrostatic interaction) for the process.16,21 The grafting-from strategy via surface-initiated polymerization can afford diverse antifouling polymer surfaces but with complicated, rigorous synthesis or fabrication procedures and imperfect attachment of side chains.17,18,22 More importantly, the above-mentioned means are less © XXXX American Chemical Society

applicable to larger surfaces such as a ship hull. Thus, the grafting-onto method via physical adsorption is particularly regarded as a better choice for the preparation of antifouling surfaces because of its easy operation, low and effective cost, and suitability for large areas. Improving the efficiency of antifouling polymer surfaces is still being urgently pursued. Because of the amphiphilic characteristic of proteins and organisms, individual hydrophilic or hydrophobic polymer surfaces have proven to be inefficient to suppress biofouling.23 Gleason et al. reported the preparation of random amphiphilic thin polymer surfaces via the copolymerization of hydrophilic 2-hydroxyethyl methacrylate with hydrophobic perfluorodecylacrylate.24 Their results suggested that surfaces with compositional heterogeneities on the length scale of the foulant would strongly limit adsorption events, that is to say, amphiphilic polymer surfaces with the combination of hydrophilic and hydrophobic components Received: March 7, 2017 Accepted: April 18, 2017 Published: April 18, 2017 A

DOI: 10.1021/acsami.7b03258 ACS Appl. Mater. Interfaces XXXX, XXX, XXX−XXX

Research Article

ACS Applied Materials & Interfaces Scheme 1. Synthesis of b-PFMA−PEO Asymmetric Molecular Brush

specialty acrylate monomer of Br-acrylate-alkyne bearing a double bond, a 2-bromopropionate functionality, and an alkynyl, which was prepared using tBBPMA,41 trifluoroacetic acid, and propargyl bromide as starting materials via a two-step reaction (Scheme 1). The structure of the Br-acrylate-alkyne 2 trifunctional acrylate monomer was verified using 1H (Figure S1A) and 13C (Figure S2) NMR. The resonance signals of the double bond at 6.00 and 6.48 ppm (1H NMR) and 129.0 and 134.1 ppm (13C NMR), CHBr at 4.42 ppm, and CH at 2.50 ppm clearly evidenced the successful synthesis of the Bracrylate-alkyne monomer. On the basis of Br-acrylate-alkyne 2 monomer, two poly(Bracrylate-alkyne) 3 homopolymers with different molecular weights were prepared by reversible addition−fragmentation chain transfer (RAFT) homopolymerization in toluene at 70 °C using AIBN as the initiator and CDB as the chain transfer agent (CTA) as summarized in Table S1. The degrees of polymerization (DPs) of the two samples are 11 and 21, accurately determined using 1H NMR. The dithiobenzoate end group originating from the CTA was removed by AIBN to avoid the possible impact on the next reaction.42 Both gel permeation chromatography (GPC) curves (Figure S3) show a unimodal and symmetrical elution peak (Mw/Mn ≤ 1.30), indicative of a well-defined structure. The chemical structure of macroagent 3 containing an alkynyl functionality for Cucatalyzed azide/alkyne cycloaddition (CuAAc) “click” reaction and a 2-bromopropionate group as an atom transfer radical polymerization (ATRP)-initiating site in every repeat unit were confirmed using 1H NMR (Figure S1B) and FT-IR (Figure S4B), which further demonstrated that both functionalities remained inert during RAFT polymerization as expected. One-Shot Synthesis of a b-PFMA−PEO Asymmetric Molecular Brush. b-PFMA−PEO 4 asymmetric molecular brushes were synthesized in a one-shot system using a poly(Bracrylate-alkyne) 3 macroagent, PEO-N3, and a commercially available FMA monomer (Scheme 1) through a combination of grafting-onto43 and grafting-from44 strategies. Because of the similar catalytic system, copper(I)/ligand may simultaneously mediate two different reactions, either ATRP45 or CuAAc click reaction;46 therefore, the b-PFMA−PEO 4 asymmetric molecular brush can be directly synthesized in a one-shot system via the combination of ATRP and CuAAc click reaction.

would be more effective as antifouling materials. Additionally, a high chain density has been illustrated to be another indispensable part in the construction of antifouling polymer surfaces.21,25 Thus, with the superior antifouling performance demonstrated for the amphiphilic polymer surfaces, we hypothesize that the combination of the amphiphilic nature with dense polymeric chains would effectively improve the antifouling ability of the various pollutants attached. A molecular brush is a special type of macromolecule in which multiple polymer chains are densely attached to a linear polymer backbone.26−31 Because of its dense polymeric chains and flexible conformation,32−34 amphiphilic molecular brushes may be significantly attractive for the preparation of antifouling polymer surfaces. Nevertheless, the synthetic challenges have made it difficult to explore the antifouling performance of the surface bearing the amphiphilic molecular brush; especially, the amphiphilic asymmetric molecular brush comprising two different side chains densely distributed on the same repeat unit along the backbone.35 Herein, we present a new rationally designed antifouling surface using an amphiphilic asymmetric molecular brush of b-PFMA−PEO (brush-poly(2,2,2-trifluoroethyl methacrylate)−poly(ethylene oxide)) via the spincasting method, which makes the preparation process easy and convenient. The b-PFMA−PEO asymmetric molecular brush possesses three critical components including a dense amphiphilic dual side chain structure, a PEO side chain known for its exceptional nonfouling property,36,37 and a PFMA side chain exhibiting fouling-release property as a result of its low surface energy.38,39 We used quartz crystal microbalance (QCM) technique to quantitatively evaluate the adsorption of proteins on PFMA−PEO-functionalized sensors. The resistance ability to cell adhesion of the b-PFMA−PEO asymmetric molecular brush surface was investigated using HaCat cells. This work demonstrated that the concept of combining a PEG side chain with a fluorinated PFMA side chain along the backbone not only maintains the nonfouling property of the surfaces but also endows the surfaces with fouling release functionality.40

■

RESULTS AND DISCUSSION Preparation of Poly(Br-acrylate-alkyne) Bifunctional Macroagent. Key to our synthetic protocol is based on a B


Research Article

ACS Applied Materials & Interfaces Table 1. Synthesis of b-PFMA−PEO 4 Asymmetric Molecular Brushesa

a b

entry

macroagent

time (h)

Mn,PEO‑N3 (g/mol)

Mn,GPCb (g/mol)

Mw/Mnb

NFMAc

Mn,NMRd (g/mol)

4a 4b 4c 4d 4e

3a 3a 3b 3b 3b

3.0 4.5 3.0 4.5 3.0

775 775 775 775 2025

75 500 84 500 98 300 148 500 132 900

1.38 1.41 1.41 1.49 1.42

26 40 28 43 26

59 800 85 700 121 100 174 100 140 300

Reaction temperature: 50 °C, solvent: DMF, feeding ratio: [FMA]/[PEO-N3]/[−Br]/[CuBr]/[HMTETA] = 150:3.5:1:2:2, [−CCH] = [−Br]. Measured by GPC at 35 °C in THF. cThe number of FMA repeat units per PFMA side chain obtained from 1H NMR. dObtained from 1H NMR.

It should be noted that the whole synthesis process does not involve any protection group chemistry, and polymeric functionality transformation yet enables an efficient, scalable preparation of PEO−PFMA-containing asymmetric molecular brushes. During the click reaction, the usage of PEO-N3 with a low steric congestion and a “thinner” structure can reduce unfavorable steric influence and maintain the high efficiency of the click reaction. Moreover, a relatively high feeding ratio of PEO-N3 to alkynyl (3.5:1) was used to further improve the efficiency of the click reaction.47 The grafting density of PEO side chain was measured by GPC using PS (Mn = 3790 g/mol) as an internal standard. Because PS remained inert during the whole process, the percentage of the reacted PEO-N3 could be estimated by comparing the normalized peak areas of PEO-N3 and PS (set as 1.0000) before and after click reaction in GPC curves (Figure S5 and Table S2). In this work, the conversion of PEO-N3 is 26.32% so that the grafting density of the PEO side chain is 92.12% within 3 h (Table S2), which means that the pendent alkynyls of macroagent 3b were almost consumed for linking PEO side chains via the click reaction. This point was also supported by the disappearance of typical FT-IR signals of alkynyl at 3286 and 2127 cm−1 (Figure S4A) and azide at 2110 cm−1 (Figure S4B) after the one-pot reaction (Figure S4C), affirming the high efficiency of the CuAAc click reaction. In combination with the quantitative initiation efficiency of ATRP,41 it can be concluded that both PEO and PFMA side chains are densely distributed on the same unit along the backbone. ATRP kinetics of FMA initiated by poly(Br-acrylate-alkyne) 3b was investigated by GC (see details in Supporting Information). Figure S6 shows a linear relationship of ln([M]0/[M]t) versus time, that is, first-order polymerization kinetics. This observation demonstrates that ATRP of FMA is controllable in the current one-shot system accompanying with the CuAAc click reaction. All GPC curves of b-PFMA−PEO 4 asymmetric molecular brushes (Figure S7) show a unimodal and symmetric elution peak, with relatively narrow molecular weight distributions (Mw/Mn < 1.50, Table 1), which implied the absence of intermolecular coupling reactions.48 The resultant after the one-pot ATRP/CuAAc reaction was characterized using 1H NMR, and all typical proton resonance signals corresponding to both PEO and PFMA side chains appeared in Figure 1. Moreover, 1H NMR was used to give the length of the PFMA side chain according to the following equation (Sc and Se represent the integral areas of peaks “c” and “e”, respectively; the grafting density of the PEO side chain is 92.12%; see Table S2). NFMA = (3 × 92.12% × Se)/(2Sc)

Figure 1. 1H NMR spectrum of the b-PFMA−PEO 4 asymmetric molecular brush in CD2Cl2.

As listed in Table 1, a series of b-PFMA−PEO 4 asymmetric molecular brushes were synthesized for investigating the structural effect of the DP of the backbone, the length of PEO and PFMA side chains. Brushes with different lengths of the PFMA side chain were synthesized by varying the polymerization time using different poly(Br-acrylate-alkyne) 3 macroagents. Brushes 4a, 4c, and 4e possess PFMA side chains containing approximately 26 FMA repeat units, whereas the number of FMA repeat units of PFMA side chains in brushes 4b and 4d is approximately 40. Brushes 4c and 4e consist of the same number of PFMA side chains with a similar length using the same macroagent, whereas the lengths of the PEO side chains in brushes 4c and 4e are different. It should also be mentioned that considering the good versatility of click reaction and ATRP, a wide range of monomers can be envisioned via this synthetic strategy to construct a broad scope of asymmetric molecular brush. Preparation of Asymmetric Molecular Brush Surfaces. In the present work, asymmetric molecular brush surfaces were prepared by spin-casting a dilute solution of brushes onto a surface. The characteristics of the resultant surfaces were determined using atomic force microscopy (AFM), static water contact angle, and X-ray photoelectron spectroscopy (XPS). AFM images of the surfaces prepared on the ITO substrate and SiO2 quartz crystal microbalance with dissipation (QCM-D) sensor (Figure 2) indicated that the roughness of surfaces was just about 1 and 3 nm, respectively, that is, both surfaces were relatively smooth.32 Static water contact angles and the atomic composition of the surfaces grafted with various amphiphilic brushes are summarized in Table S3. The contact angle of water on the surfaces exhibited a transition from 91.1° to 101.7°. We can clearly notice that the contact angle is obviously

(1) C


Research Article

ACS Applied Materials & Interfaces

Figure 2. AFM height images for b-PFMA−PEO 4a asymmetric molecular brush coatings (A) on ITO substrates as cast coatings (scale: 1 μm × 1 μm) and (B) on SiO2-coated QCM-D sensor as cast coatings (scale: 1 μm × 1 μm).

dependent on the length of the PEO and PFMA side chains. While increasing the length of the PFMA side chain, the contact angle of water also increased as follows: 4a (96.6°) to 4b (101.7°) and 4c (94.3°) to 4d (99.6°). On the other hand, the contact angle of water decreased as the length of the PEO side chain increased: 4c (94.3°) to 4e (91.1°). Similarly, the fluorine content near the top surface was also dependent on the length of the PEO and PFMA side chains: 4a (7.71%) to 4b (13.26%), 4c (7.06%) to 4d (9.08%), and 4c (7.06%) to 4e (6.37%). Resistance of Asymmetric Molecular Brush Surfaces to Protein Adsorption. QCM-D was used to investigate the real-time adsorption behavior of bovine serum albumin (BSA) onto SiO2 sensors coated with different brushes from phosphate-buffered saline (PBS) solution. As can be seen from Figure 3, QCM-D time traces of all five b-PPFMA−PEO 4 asymmetric molecular brush surfaces or the bare sensor show a sharp negative shift in the fifth harmonic frequency of the crystal when the sensors were exposed to a solution of BSA. The decrease in the harmonic frequency of the sensor indicated a mass increase on the surface, which was physically correlated with the increased mass of protein vibrating with the sensor.24 After the frequency curves were stabilized for 1 h, the surfaces were rinsed with PBS to remove the loosely bound BSA, resulting in an increase in frequency. The mass of adsorbed proteins on different surfaces before and after rinsing with PBS was accurately determined using the Voigt viscoelastic model as plotted in Figure 4. The antifouling activities of b-PFMA−PEO 4 asymmetric molecular brush surfaces are highly dependent on their molecular structure such as the DP of the backbone and the length of the PEO and PFMA side chains. Before rinsing with PBS, by comparing 4a (588 ng/cm2) and 4c (491 ng/cm2), 4b (617 ng/cm2) and 4d (495 ng/cm2), it is clear that a higher DP of backbone, that is, more side chains, strengthens the antifouling performance, so less protein adsorption is observed

Figure 3. Representative time traces of frequency shifts in the fifth harmonic of the QCM-D crystal sensor coated with b-PFMA−PEO 4 asymmetric molecular brush surfaces in BSA protein solutions.

for the 4c and 4d asymmetric molecular brush surfaces. The length of the PFMA side chain is also important for the antifouling performance. Before rinsing with PBS, brushes with longer PFMA side chains show more protein adsorption: 4b (617 ng/cm2) to 4a (588 ng/cm2) and 4d (495 ng/cm2) to 4c (491 ng/cm2). However, after rinsing with PBS, to remove the loosely bound BSA, surfaces with longer PFMA side chains [4b (617−302 ng/cm2) and 4d (495−275 ng/cm2)] obviously exhibit fouling-release function because of their low surface energy so that the protein is easier to be washed, resulting in a greatly decreased frequency. In addition, the length of the PEO side chain also affects the antifouling performance, which is verified by coating asymmetric molecular brushes 4c with PEO16 (Mn = 750 g/mol) side chains and 4e with PEO44 (Mn = 2000 g/mol) side chains onto sensors for comparison. The 4e D


Research Article


cells, that is to say, the few adhered cells prefer to self-associate into clusters. The formation of the unique cell clusters may be concerned with the fact that the antifouling surfaces with the lack of adhesion site result in cell−cell adhesion interactions and present the self-association behavior of cells.49,50 For an ordinary surface, cells remain separate from other cells that receive stronger adhesion from the surface. The quantification of the number of adhered cells is used to examine the prevalence of cell adhesion on different surfaces, and the data are listed in Figure 6. The number of adhered cells

Figure 4. Protein adsorption onto the b-PFMA−PEO 4 asymmetric molecular brush surfaces before and after PBS rinse.

surface (301 ng/cm2) exhibits a better antifouling performance than the 4c surface (491 ng/cm2). Briefly, three critical factors for antifouling behaviors are informed from this study. Asymmetric molecular brush surfaces, which have a higher DP of the backbone and longer PFMA and PEO side chains, may exhibit the best antifouling performance. Most importantly, proteins adsorbed readily onto the bare sensor (1071 ng/cm2) without coating using a asymmetric molecular brush; on the contrary, all asymmetric molecular brush surfaces show a much less protein adsorption (at least 45% off, up to 75% off) for exhibiting a considerable antifouling ability. Resistance of Asymmetric Molecular Dual-Brush Surfaces to Cell Adhesion. The antifouling behavior of bPFMA−PEO 4 asymmetric molecular brush surfaces was further investigated using a cell adhesion experiment. Samples were prepared identically to ITO substrate to allow for easy visualization of cells. Different HaCaT cell morphologies were observed depending upon cellular exposure to the bare surface or the surface coated with the asymmetric molecular brush. Cells are clearly attached in large numbers to the bare surface (Figure 5A), where the rounded cells show a good spreading. However, on the b-PFMA−PEO 4 asymmetric molecular brush surface (Figure 5B−F), cells are hindered from attaching to the surface, and the remaining morphology is a cluster of several

Figure 6. Quantification of cells appearing on b-PFMA−PEO 4 asymmetric molecular brush surfaces; data are shown as mean ± standard error for five samples.

for a bare surface is 231 ± 13, whereas the numbers for the asymmetric molecular brush surfaces are all below 70 (at least 70% off, up to 90% off). This fact clearly demonstrates that the asymmetric molecular brush surfaces can significantly resist cell adhesion. Moreover, statistical analysis shows that the DP of the backbone and the length of the PEO side chain also have considerable effects on the number of cells adhered onto the surfaces. A higher DP of the backbone, that is, more PEO side chains, strengthens the cell resistance performance. Therefore, less adhered cells are observed for 4c (24 ± 7) to 4a (39 ± 7) and 4d (35 ± 6) to 4b (61 ± 5). Meanwhile, the number of adhered cells decreases with the increase in the length of PEO

Figure 5. Images of HaCaT cells grown on bare ITO (A) and b-PFMA−PEO 4 asymmetric molecular brush surfaces: (B) 4a, (C) 4b, (D) 4c, (E) 4d, and (F) 4e. E



■

side chain, that is, 4c (24 ± 7) to 4e (16 ± 4). It is important to emphasize that PEO still plays a critical role in determining the resistance ability to cell adhesion of the surface, whereas the longer PFMA side chains actually weaken the resistance to cell adhesion, that is, 4a (39 ± 7) to 4b (61 ± 5) and 4c (24 ± 7) to 4d (35 ± 6). Thus, we can conclude that optimizing the polymer composition would enhance the cell resistance performance of the asymmetric molecular brush surfaces.

■

CONCLUSIONS

■

ASSOCIATED CONTENT

REFERENCES

(1) Tribou, M.; Swain, G. The Use of Proactive in-water Grooming to Improve the Performance of Ship Hull Antifouling Coatings. Biofouling 2010, 26, 47−56. (2) Schultz, M. P.; Bendick, J. A.; Holm, E. R.; Hertel, W. M. Economic Impact of Biofouling on a Naval Surface Ship. Biofouling 2011, 27, 87−98. (3) Krishnan, S.; Weinman, C. J.; Ober, C. K. Advances in Polymers for Anti-Biofouling Surfaces. J. Mater. Chem. 2008, 18, 3405−3413. (4) Rosenhahn, A.; Schilp, S.; Kreuzer, H. J.; Grunze, M. The Role of “Inert” Surface Chemistry in Marine Biofouling Prevention. Phys. Chem. Chem. Phys. 2010, 12, 4275−4286. (5) Werner, C.; Maitz, M. F.; Sperling, C. Current Strategies towards Hemocompatible Coatings. J. Mater. Chem. 2007, 17, 3376−3384. (6) Li, L.; Yan, B.; Yang, J.; Chen, L.; Zeng, H. Novel MusselInspired Injectable Self-Healing Hydrogel with Anti-Biofouling Property. Adv. Mater. 2015, 27, 1294−1299. (7) Krishnamoorthy, M.; Hakobyan, S.; Ramstedt, M.; Gautrot, J. E. Surface-Initiated Polymer Brushes in the Biomedical Field: Applications in Membrane Science, Biosensing, Cell Culture, Regenerative Medicine and Antibacterial Coatings. Chem. Rev. 2014, 114, 10976− 11026. (8) Zhang, L.; Ning, C.; Zhou, T.; Liu, X.; Yeung, K. W. K.; Zhang, T.; Xu, Z.; Wang, X.; Wu, S.; Chu, P. K. Polymeric Nanoarchitectures on Ti-Based Implants for Antibacterial Applications. ACS Appl. Mater. Interfaces 2014, 6, 17323−17345. (9) Carrigan, S. D.; Tabrizian, M. Reducing Nonspecific Adhesion on Cross-Linked Hydrogel Platforms for Real-Time Immunoassay in Serum. Langmuir 2005, 21, 12320−12326. (10) Voo, Z. X.; Khan, M.; Narayanan, K.; Seah, D.; Hedrick, J. L.; Yang, Y. Y. Antimicrobial/Antifouling Polycarbonate Coatings: Role of Block Copolymer Architecture. Macromolecules 2015, 48, 1055−1064. (11) Xu, B.; Feng, C.; Hu, J.; Shi, P.; Gu, G.; Wang, L.; Huang, X. Spin-Casting Polymer Brush Films for Stimuli-Responsive and AntiFouling Surfaces. ACS Appl. Mater. Interfaces 2016, 8, 6685−6692. (12) van Zoelen, W.; Buss, H. G.; Ellebracht, N. C.; Lynd, N. A.; Fischer, D. A.; Finlay, J.; Hill, S.; Callow, M. E.; Callow, J. A.; Kramer, E. J.; Zuckermann, R. N.; Segalman, R. A. Sequence of Hydrophobic and Hydrophilic Residues in Amphiphilic Polymer Coatings Affects Surface Structure and Marine Antifouling/Fouling Release Properties. ACS Macro Lett. 2014, 3, 364−368. (13) Zhao, W.; Ye, Q.; Hu, H.; Wang, X.; Zhou, F. Grafting Zwitterionic Polymer Brushes via Electrochemical Surface-Initiated Atomic-Transfer Radical Polymerization for Anti-Fouling Applications. J. Mater. Chem. B 2014, 2, 5352−5357. (14) Ma, A.; Xie, Y.; Xu, J.; Zeng, H.; Xu, H. The Significant Impact of Polydopamine on the Catalytic Performance of the Carried Au Nanoparticles. Chem. Commun. 2015, 51, 1469−1471. (15) Li, L.; Yan, B.; Zhang, L.; Tian, Y.; Zeng, H. Mussel-Inspired Antifouling Coatings Bearing Polymer Loops. Chem. Commun. 2015, 51, 15780−15783. (16) Maity, S.; Nir, S.; Zada, T.; Reches, M. Self-Assembly of a Tripeptide into a Functional Coating that Resists Fouling. Chem. Commun. 2014, 50, 11154−11157. (17) Kobayashi, M.; Terayama, Y.; Yamaguchi, H.; Terada, M.; Murakami, D.; Ishihara, K.; Takahara, A. Wettability and Antifouling Behavior on the Surfaces of Superhydrophilic Polymer Brushes. Langmuir 2012, 28, 7212−7222. (18) Kuang, J.; Messersmith, P. B. Universal Surface-Initiated Polymerization of Antifouling Zwitterionic Brushes Using a MusselMimetic Peptide Initiator. Langmuir 2012, 28, 7258−7266. (19) Cho, J. H.; Shanmuganathan, K.; Ellison, C. J. Bioinspired Catecholic Copolymers for Antifouling Surface Coatings. ACS Appl. Mater. Interfaces 2013, 5, 3794−3802. (20) Ding, X.; Yang, C.; Lim, T. P.; Hsu, L. Y.; Engler, A. C.; Hedrick, J. L.; Yang, Y.-Y. Antibacterial and Antifouling Catheter Coatings Using Surface Grafted PEG-b-cationic Polycarbonate Diblock Copolymers. Biomaterials 2012, 33, 6593−6603.

In summary, the preparation of synergistic antifouling surfaces coated with b-PFMA−PEO asymmetric molecular brushes is reported. By using a new poly(Br-acrylate-alkyne) macroagent with a 2-bromopropionate moiety as an ATRP-initiating site and an alkynyl as a click reaction functionality, the orthogonal overlay of ATRP and CuAAc click reaction allows the one-shot synthesis of b-PFMA−PEO asymmetric molecular brushes. Spin-cast b-PFMA−PEO asymmetric molecular brush surfaces exhibit a synergistic antifouling property: PEO side chains endow the surface with a nonfouling characteristic, whereas PFMA side chains exhibit fouling-release functionality because of their low surface energy. With compositional heterogeneities, all asymmetric molecular brush surfaces show considerable antifouling performance with much less protein adsorption (at least 45% off) and cell adhesion (at least 70% off) in comparison with the bare surface. Moreover, asymmetric molecular brush surfaces with a higher DP of the backbone and longer PEO side chains show the best protein adsorption resistance (75% off) and cell adhesion resistance (90% off).

S Supporting Information *

The Supporting Information is available free of charge on the ACS Publications website at DOI: 10.1021/acsami.7b03258. Instruments and materials, experimental details, NMR spectra, FT-IR and GPC result, and additional data (PDF)

■

Research Article

AUTHOR INFORMATION

Corresponding Authors

*E-mail: [email protected]. Phone: +86-21-55665280. Fax: +86-21-65640293 (J.H.). *E-mail: [email protected]. Phone: +86-21-54925310. Fax: +86-21-64166128 (X.H.). ORCID

Xiaoyu Huang: 0000-0002-9781-972X Notes

The authors declare no competing financial interest.

■

ACKNOWLEDGMENTS The authors thank the financial support from National Basic Research Program of China (2015CB931900), International Science & Technology Cooperation Program of China (2014DFE40130), National Natural Science Foundation of China (21474127 and 51373035), Strategic Priority Research Program of Chinese Academy of Sciences (XDB20020000), and Shanghai Scientific and Technological Innovation Project (14JC1493400, 16JC1402500, 14520720100, and 16520710300). F


Research Article

ACS Applied Materials & Interfaces (21) Saxer, S.; Portmann, C.; Tosatti, S.; Gademann, K.; Zürcher, S.; Textor, M. Surface Assembly of Catechol-Functionalized Poly(Llysine)-graft-poly(ethylene glycol) Copolymer on Titanium Exploiting Combined Electrostatically Driven Self-Organization and Biomimetic Strong Adhesion. Macromolecules 2010, 43, 1050−1060. (22) Rastogi, A.; Nad, S.; Tanaka, M.; Da Mota, N.; Tague, M.; Baird, B. A.; Abruña, H. D.; Ober, C. K. Preventing Nonspecific Adsorption on Polymer Brush Covered Gold Electrodes Using a Modified ATRP Initiator. Biomacromolecules 2009, 10, 2750−2758. (23) Ramsden, J. J. Puzzles and Paradoxes in Protein Adsorption. Chem. Soc. Rev. 1995, 24, 73−78. (24) Baxamusa, S. H.; Gleason, K. K. Random Copolymer Films with Molecular-Scale Compositional Heterogeneities that Interfere with Protein Adsorption. Adv. Funct. Mater. 2009, 19, 3489−3496. (25) Pasche, S.; De Paul, S. M.; Vörös, J.; Spencer, N. D.; Textor, M. Poly(L-lysine)-graf t-poly(ethylene glycol) Assembled Monolayers on Niobium Oxide Surfaces: A Quantitative Study of the Influence of Polymer Interfacial Architecture on Resistance to Protein Adsorption by ToF-SIMS and in Situ OWLS. Langmuir 2003, 19, 9216−9225. (26) Wintermantel, M.; Gerle, M.; Fischer, K.; Schmidt, M.; Wataoka, I.; Urakawa, H.; Kajiwara, K.; Tsukahara, Y. Molecular Bottlebrushes. Macromolecules 1996, 29, 978−983. (27) Kawaguchi, S.; Akaike, K.; Zhang, Z.-M.; Matsumoto, H.; Ito, K. Water Soluble Bottlebrushes. Polym. J. 1998, 30, 1004−1007. (28) Bhattacharya, A.; Misra, B. N. Grafting: A Versatile Means to Modify Polymers Techniques, Factors and Applications. Prog. Polym. Sci. 2004, 29, 767−814. (29) Ishizu, K. Architecture of Multi-Component Copolymer Brushes: Synthesis, Solution Properties and Application for Nanodevices. Polym. J. 2004, 36, 775−792. (30) Lee, H.-i.; Pietrasik, J.; Sheiko, S. S.; Matyjaszewski, K. StimuliResponsive Molecular Brushes. Prog. Polym. Sci. 2010, 35, 24−44. (31) Pesek, S. L.; Li, X.; Hammouda, B.; Hong, K.; Verduzco, R. Small-Angle Neutron Scattering Analysis of Bottlebrush Polymers Prepared via Grafting-Through Polymerization. Macromolecules 2013, 46, 6998−7005. (32) Li, X.; Prukop, S. L.; Biswal, S. L.; Verduzco, R. Surface Properties of Bottlebrush Polymer Thin Films. Macromolecules 2012, 45, 7118−7127. (33) Xu, B.; Gu, G.; Feng, C.; Jiang, X.; Hu, J.; Lu, G.; Zhang, S.; Huang, X. (PAA-g-PS)-co-PPEGMEMA Asymmetric Polymer Brushes: Synthesis, Self-assembly, and Encapsulating Capacity for Both Hydrophobic and Hydrophilic Agents. Polym. Chem. 2016, 7, 613− 624. (34) Tang, S.; Puryear, W. B.; Seifried, B. M.; Dong, X.; Runstadler, J. A.; Ribbeck, K.; Olsen, B. D. Antiviral Agents from Multivalent Presentation of Sialyl Oligosaccharides on Brush Polymers. ACS Macro Lett. 2016, 5, 413−418. (35) Xie, M.; Dang, J.; Han, H.; Wang, W.; Liu, J.; He, X.; Zhang, Y. Well-Defined Brush Copolymers with High Grafting Density of Amphiphilic Side Chains by Combination of ROP, ROMP, and ATRP. Macromolecules 2008, 41, 9004−9010. (36) Ma, H.; Hyun, J.; Stiller, P.; Chilkoti, A. “Non-Fouling” Oligo(ethylene glycol)-Functionalized Polymer Brushes Synthesized by Surface-Initiated Atom Transfer Radical Polymerization. Adv. Mater. 2004, 16, 338−341. (37) Cho, Y.; Sundaram, H. S.; Weinman, C. J.; Paik, M. Y.; Dimitriou, M. D.; Finlay, J. A.; Callow, M. E.; Callow, J. A.; Kramer, E. J.; Ober, C. K. Triblock Copolymers with Grafted Fluorine-Free, Amphiphilic, Non-Ionic Side Chains for Antifouling and FoulingRelease Applications. Macromolecules 2011, 44, 4783−4792. (38) Youngblood, J. P.; Andruzzi, L.; Ober, C. K.; Hexemer, A.; Kramer, E. J.; Callow, J. A.; Finlay, J. A.; Callow, M. E. Coatings Based on Side-Chain Ether-Linked Poly(ethylene glycol) and Fluorocarbon Polymers for the Control of Marine Biofouling. Biofouling 2003, 19, 91−98. (39) Grozea, C. M.; Walker, G. C. Approaches in Designing NonToxic Polymer Surfaces to Deter Marine Biofouling. Soft Matter 2009, 5, 4088−4100.

(40) Wang, Y.; Betts, D. E.; Finlay, J. A.; Brewer, L.; Callow, M. E.; Callow, J. A.; Wendt, D. E.; DeSimone, J. M. Photocurable Amphiphilic Perfluoropolyether/Poly(ethylene glycol) Networks for Fouling-Release Coatings. Macromolecules 2011, 44, 878−885. (41) Zhang, Y.; Shen, Z.; Yang, D.; Feng, C.; Hu, J.; Lu, G.; Huang, X. Convenient Synthesis of PtBA-g-PMA Well-Defined Graft Copolymer with Tunable Grafting Density. Macromolecules 2010, 43, 117−125. (42) Perrier, S.; Takolpuckdee, P.; Mars, C. A. Reversible Addition− Fragmentation Chain Transfer Polymerization: End Group Modification for Functionalized Polymers and Chain Transfer Agent Recovery. Macromolecules 2005, 38, 2033−2036. (43) Wu, G.; Chen, S.-C.; Zhan, Q.; Wang, Y.-Z. Well-Defined Amphiphilic Biodegradable Comb-Like Graft Copolymers: Their Unique Architecture-Determined LCST and UCST Thermoresponsivity. Macromolecules 2011, 44, 999−1008. (44) Rzayev, J. Synthesis of Polystyrene−Polylactide Bottlebrush Block Copolymers and Their Melt Self-Assembly into Large Domain Nanostructures. Macromolecules 2009, 42, 2135−2141. (45) Wang, J.-S.; Matyjaszewski, K. Controlled/“Living” Radical Polymerization. Atom Transfer Radical Polymerization in the Presence of Transition-Metal Complexes. J. Am. Chem. Soc. 1995, 117, 5614− 5615. (46) Lutz, J.-F. 1,3-Dipolar Cycloadditions of Azides and Alkynes: A Universal Ligation Tool in Polymer and Materials Science. Angew. Chem., Int. Ed. 2007, 46, 1018−1025. (47) Gao, H.; Matyjaszewski, K. Synthesis of Molecular Brushes by “Grafting onto” Method: Combination of ATRP and Click Reactions. J. Am. Chem. Soc. 2007, 129, 6633−6639. (48) Cheng, G.; Böker, A.; Zhang, M.; Krausch, G.; Müller, A. H. E. Amphiphilic Cylindrical Core−Shell Brushes via a “Grafting From” Process using ATRP. Macromolecules 2001, 34, 6883−6888. (49) Coad, B. R.; Lu, Y.; Glattauer, V.; Meagher, L. SubstrateIndependent Method for Growing and Modulating the Density of Polymer Brushes from Surfaces by ATRP. ACS Appl. Mater. Interfaces 2012, 4, 2811−2823. (50) Rodda, A. E.; Ercole, F.; Nisbet, D. R.; Forsythe, J. S.; Meagher, L. Optimization of Aqueous SI-ATRP Grafting of Poly(oligo(ethylene glycol)methacrylate) Brushes from Benzyl Chloride Macroinitiator Surfaces. Macromol. Biosci. 2015, 15, 799−811.

G


Fouling-Release Surface

Recommend Documents